Sub-calibred projectiles with multiple supports

ABSTRACT

The technical scope of the invention is that of sub-calibred projectiles comprising a calibred sabot formed of at least two segments and surrounding a sub-calibred penetrator. This projectile is characterized in that the sabot incorporates at least three substantially calibred support seats, axially spaced from one another. The distance between said two supports the furthest apart is greater than or equal to 3 calibers. At least one support seat, called median support seat, is formed by a push plate (PP) incorporating at least one groove to receive a band, said push plate axially located between said two other support seats.

BACKGROUND OF THE INVENTION

1.—Field of Invention

The technical scope of the invention is that of sub-calibred projectilescomprising a calibred sabot formed of at least two segments andsurrounding a sub-calibred penetrator.

2.—Description of the Related Art

Such projectiles are well known and are usually termed fin-projectilessince the penetrator is stabilized using a fin tailpiece.

The sabot generally has a calibred push plate onto which a sealing bandis mounted. The sabot also incorporates another calibred support seatallowing the projectile to be guided in the barrel and preventing theaxis of the penetrator from becoming misaligned with respect to thebarrel axis.

This other support seat may be found to the fore of the guiding plate asdescribed hereafter with reference to FIG. 1 (so-called “pull-push”sabot).

It may also be found to the rear of the guiding plate as describedhereafter with reference to FIG. 2 (so-called “pull” sabot).

Fin-stabilized projectiles are currently sought to have improvedperformances both with respect to the velocity of the penetrator and toits piercing capabilities.

An increase in the velocity may be obtained by increasing the mass ofpropellant charge, thereby conducting to the lead of projectiles inwhich the push plate is positioned far forwards.

The push plate of the sabot is thus introduced into the gun barrel wellbefore the rear support seat is able to stabilize the sabot. There istherefore a risk during the first moments of the interior ballisticphase of the projectile pivoting around the hinge formed by the band.Such pivoting leads to the incorrect angular positioning of theprojectile in the barrel which may cause oscillations disturbing theflight stability of the projectile.

Research to improve performances also lead to the design of projectilesincorporating a very long penetrator whose rear part penetrates deeplyinto the propellant charge. The sabot must in this case be reinforced atits rear part so as to drive the inertia of the penetrator, therebycompromising the light weight of the sabot.

Moreover, an elongated penetrator causes bending oscillations to therear part of the projectile in the barrel thereby also causing adisturbance to the flight stability of the projectile.

SUMMARY OF THE INVENTION

The aim of the projectile is to propose a projectile that does notsuffer from such drawbacks.

Thus, the projectile according to the invention incorporates a sabot ofreduced mass but which nevertheless ensures improved guidance for theprojectile in the barrel and avoids positioning obliquities andvibrations of the penetrator.

Thus, the invention relates to a sub-calibre projectile comprising acalibred sabot formed of at least two segments and surrounding asub-calibred penetrator, such projectile wherein the sabot incorporatesat least three substantially calibred support seats, axially spaced fromone another.

The distance between the two supports the furthest apart will preferablybe greater than-or equal to 3 calibers.

According to a particular embodiment at least one support seat, calledthe median support seat, is formed by a push plate incorporating atleast one groove to receive a band, such push plate axially locatedbetween two other support seats.

Advantageously, the push plate will be positioned at a distance from amedian transverse plane PM, such plane being orthogonal to thepenetrator and passing through the center of gravity of the fullprojectile, such distance being between 0.5 and 1.5 calibers.

A forward support seat may be constituted by radial arms evenly spacedangularly around the sabot.

Each arm may carry a foot of a plastic material at its end ensuring theguidance of the sabot in the barrel.

A rear support seat may be constituted by radial studs, evenly spacedangularly around the sabot.

Each radial stud may be integral with a segment of the sabot.

Alternatively, each radial stud may be formed by the juxtaposition oftwo parts, each integral with a separate segment of the sabot.

Each radial stud may carry a foot of a friction resistant material, forexample steel, ensuring the guidance of the sabot in the barrel.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will become more apparent from the following descriptionof the embodiments, such description made with reference to the appendeddrawings, in which:

FIGS. 1 and 2 show a longitudinal section of two projectiles accordingto prior art positioned in a gun barrel,

FIGS. 3 a and 3 b show a longitudinal section of a projectile accordingto a first embodiment of the invention, FIG. 3 a shows the projectilepositioned in the barrel and FIG. 3 b shows the projectile inside thebarrel during firing,

FIGS. 4 a and 4 b show a longitudinal section of a projectile accordingto a second embodiment of the invention, FIG. 4 a shows the projectilepositioned in the barrel and FIG. 4 b shows the projectile inside thebarrel during firing,

FIG. 5 a and 5 b show cross sections of different variant embodiment ofthe rear support seats,

FIG. 6 a and 6 b show partial longitudinal and cross sections of oneembodiment of a rear support seat,

FIGS. 7 a and 7 b show partial longitudinal and cross sections anotherembodiment of a rear support seat.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIGS. 1 and 2 show two fin-stabilized projectiles according to priorart.

The projectile 1 shown in FIG. 1 is a classical projectile incorporatinga sabot 2 formed of three sectors surrounding a penetrator 4 fitted witha fin tail piece 5.

The sabot 2 incorporates a cup-shaped forward support seat 6 with acircular rim substantially of the same diameter as the gun barrel 7. Thesabot 2 also incorporates a rear support seat forming a push plate PPonto which the pressure of the propulsive gases is applied.

This push plate PP incorporates a groove receiving a band 8 ensuringgas-tightness.

This sabot 2 is of the “pull-push” type, which means that the push platePP is axially located substantially at or slightly to the rear of amedian traverse plane PM which is the orthogonal plane to the penetrator4 through the center of gravity of the full projectile.

We see that when this projectile is positioned for firing in the gunbarrel the two support seats are in contact with the barrel. However,the length of the penetrator 4 still in the chamber 10 of the gun issubstantial. Bending oscillations to the rear part of the penetratorwill occur during firing thereby disturbing the flight stability of thepenetrator. Solutions implemented to date have led to the rigidity ofthe rear part of the sabot being reinforced by increasing the thicknessof the sabot thereby making it heavier.

The projectile 1 shown in FIG. 2 has an analogous overall structure andalso comprises a sabot 2 formed of three segments surrounding apenetrator 4. It differs from the previous one in that its forwardsupport seat is constituted by the push plate PP, whereas the rearsupport seat is constituted by three radial studs 9 integral with thesabot 2 and substantially calibred.

Such a sabot is of the “pull” type. In fact, the push plate PP carryingthe band 8 is here much to the fore of the median traverse plane PM,orthogonal to the penetrator 4 through the center of gravity of the fullprojectile.

We see that when the projectile is position in the gun barrel (as shownin FIG. 2), the rear support seat is in the chamber. It can only ensureits guidance function when the projectile is further inside the gunbarrel. This results in the projectile pivoting around the band 8.

In both cases, the guidance length 1 which is the distance between thetwo supports is of around 1.5 calibers for the pull sabot projectileaccording to FIG. 2 and 2.5 calibers for the pull-push sabot projectilein FIG. 1.

A first embodiment of a projectile 1 according to the invention is shownin FIGS. 3 a and 3 b. This projectile has a “pull-push” sabot like theone in FIG. 1. It differs from the latter in that the sabot 2incorporates three substantially calibred support seats that are axiallyspaced from one another.

The projectile thus comprises:

-   -   a cup-shaped forward support seat 6 with a circular rim        substantially of the diameter of the gun barrel 7,    -   a median support seat constituted by the push plate PP carrying        the band 8,    -   a rear support seat constituted by radial studs 11 evenly spaced        angularly around the sabot 2.

The result of such a configuration is that when the projectile 1 isinside the barrel 7 (FIG. 3 b) the penetrator is held with respect tothe barrel by three guiding supports (6, PP and 11).

Oscillations to the rear part of the penetrator, even for penetrators ofgreat length (over 30 times their diameter), are avoided.

The guidance length L, that is the distance between the two supportsthat are the furthest apart (6 and 11) is greater than or equal to 3calibers, that is substantially twice as long as that of prior guidance1 (FIG. 1).

The rear studs 11 have a mass that is lower than the mass of the sabotthat would have been necessary at the rear part to prevent thepenetrator from oscillating. The projectile according to the inventionhas thus improved rigidity whilst being reduced in mass.

So as to prevent the rear studs 11 from deteriorating during the passageof the forcing cone, each stud 11 will be given a foot 14 of a resistantmaterial, for example steel.

A second embodiment of a projectile 1 according to the invention isshown in FIGS. 4 a and 4 b. This projectile is a “pull” sabot projectilelike the one in FIG. 2. It differs from the latter in that the sabot 2incorporates three substantially calibred support seats that are axiallyspaced from one another.

The projectile thus comprises:

-   -   a rear support seat constituted by radial studs 9 evenly spaced        angularly around the sabot 2,    -   a median support constituted by the push plate PP carrying the        band 8,    -   a forward support seat constituted by radial arms 12 evenly        spaced angularly around the sabot 2.

Each arm 12 carries a foot 13 of a plastic material at its end thatensures the guidance of the sabot in the barrel 7. Once again, theresult of this configuration is that when the projectile 1 is inside thebarrel 7 (FIG. 4 b) the penetrator is held in position with respect tothe barrel by three guiding supports (9, PP and 12).

Oscillations to the rear part of the penetrator, even for penetrators ofgreat length (over 30 times their diameter), are avoided.

The guidance length L, that is the distance between the two supportsthat are the furthest apart (9 and 12) is greater than or equal to 3calibers.

Moreover, the presence of arms 12 forming the guidance support preventthe projectile from being misaligned when being set into position forfiring (FIG. 4 b).

The distance L1 between the forward support 12 and median support PP isthus greater than or equal to 1.5 calibers.

The mass of the arms 12 is reduces and therefore does not add excessiveweight to the sabot. The projectile according to the invention thus hasimproved rigidity whilst be of a reduced mass.

Additionally, the push plate PP of this sabot is positioned at adistance from the median traverse plane PM (plane orthogonal to thepenetrator and through the center of gravity of the full projectile)that is between 0.5 and 1.5 calibers.

Such an arrangement allows the sabot's mass to be optimized. Thus, thepush plate PP of the projectile is forward of the gun's forcing cone 16when the ammunition is set into the firing position.

Computations will verify that the optimal gain in mass for a 120 mmcalibre sabot is obtained by moving the push plate forward by around 80mm with respect to its usual position at the forcing cone 16. Thisresults in a reduction is the weight of the sabot of 15 to 20% for ananalogous production cost.

It will be possible for the arms 12 to be given a pocket-shaped profileto receive the aerodynamic flow upon exiting the weapon. Such anarrangement allows the separation of the sabot segments to be separatedupon exiting the gun barrel. So as to prevent the rear studs 9 fromdeteriorating during the passage of the forcing cone 16, each stud 9will be given a foot 14 of a resistant material, for example steel.

FIGS. 5 a and 5 b show a cross section of two variant embodiments of therear supports 9 or 11.

Each radial stud 9 or 11 forming the rear support may thus be integralwith a single segment 2 a, 2 b or 2 c of the sabot 2 as shown in FIG. 5a.

Alternatively, each radial stud 9 or 11 may be formed by thejuxtaposition of two parts, each integral with a separate segments ofthe sabot 2 a, 2 b or 2 c, as shown in FIG. 5 b.

Each rear radial stud 9 or 11 will preferably be given a foot 14 ofresistant material, for example steel, that will ensure the guidance ofthe sabot in the barrel.

FIGS. 6 a and 6 b thus show the rear studs 9 or 11 provided with feet 14made in the form of screws introduced into female threadings carried inthe studs 9 or 11.

FIGS. 7 a and 7 b show the rear studs 9 or 11 provided with feet 14 thatare all made in the form of pads with a dove-tailed base 15 cooperatingwith a matching-shaped groove arranged in the extremity of the stud 9 or11.

It is naturally possible for a projectile incorporating more than threesupport seats to be designed. It is also possible for a projectileincorporating three support seats in which the push plate carrying theband constitutes the foremost or rearmost support.

1. A sub-calibre projectile comprising a clibred sabot formed of atleast two segments and surrounding a sub-calibred penetrator to be firedin a barrel, characterized in that said sabot incorporates at leastthree substantially calibred support seats, then a forward, median andrear support seats, axially spaced from one another.
 2. A projectileaccording to claim 1, characterized in that the distance between saidtwo supports the furthest apart is greater than or equal to 3 calibers.3. A projectile according to claim 1, characterized in that at least onesupport seat, called median support seat, is formed by a push plate (PP)incorporating at least one groove to receive a band, said push plateaxially located between said two other support seats.
 4. A projectileaccording to claim 3, characterized in that said push plate (PP) ispositioned at a distance from a median transverse plane (PM), said planebeing orthogonal to said penetrator and passing through the center ofgravity of said projectile, said distance being between 0.5 and 1.5calibers.
 5. A projectile according to claim 4, characterized in thatsaid forward support seat is constituted by radial arms evenly spacedangularly around said sabot.
 6. A projectile according to claim 5,characterized in that each said arm carries a foot of a plastic materialat its end ensuring the guidance of said sabot in said barrel.
 7. Aprojectile according to claim 1, characterized in that said rear supportseat is constituted by radial studs, evenly spaced angularly around saidsabot.
 8. A projectile according to claim 7, characterized in that eachsaid radial stud is integral with a segment of said sabot.
 9. Aprojectile according to claim 7, characterized in that each said radialstud formed by the juxtaposition of two parts, each integral with aseparate segment of said sabot.
 10. A projectile according to claim 9,characterized in that each said radial stud carries a foot of a frictionresistant material, for example steel, ensuring the guidance of saidsabot in said barrel.